Vassilis Kostakos

Learn More
Tangible user interfaces are portals to digital information. In the future, securing access to such material will be an important concern. This paper describes the design, implementation and evaluation of a PIN entry system based on audio or haptic cues that is suitable for integration into such physical systems. The current implementation links movements(More)
Victims, volunteers, and relief organizations are increasingly using social media to report and act on large-scale events, as witnessed in the extensive coverage of the 2010–2012 Arab Spring uprisings and 2011 Japanese tsunami and nuclear disasters. TwitterA feeds consist of short messages, often in a nonstandard local language, requiring novel techniques(More)
This study employs hierarchical cluster analysis, strategic diagrams and network analysis to map and visualize the intellectual landscape of the CHI conference on Human Computer Interaction through the use of co-word analysis. The study quantifies and describes the thematic evolution of the field based on a total of 3152 CHI articles and their associated(More)
We approach the design of ubiquitous computing systems in the urban environment as integral to urban design. To understand the city as a system encompassing physical and digital forms and their relationships with people’s behaviours, we are developing, applying and refining methods of observing, recording, modelling and analysing the city, physically,(More)
We present Ubinion, a service that utilizes large public interactive displays to enable young people to give personalized feedback on municipal issues to local youth workers. It also facilitates discussion and sharing the feedback online using modern social networking services. We present the motivation and rationale behind Ubinion and analyze the results(More)
In this paper we describe a platform that enables us to systematically study online social networks alongside their real-world counterparts. Our system, entitled Cityware, merges users’ online social data, made available through Facebook, with mobility traces captured via Bluetooth scanning. Furthermore, our system enables users to contribute their own(More)
Mobile phone user interfaces typically show an icon to indicate remaining battery, but not the amount of time the device can be used for, often forcing users to make faulty estimates and predictions about battery life. Here we report on two studies that capture users' experiences with a user-centered battery interface design. In Study 1, we analyze 12(More)
Open mobile platforms such as Android currently suffer from the existence of multiple versions, each with its own peculiarities. This makes the comprehensive testing of interactive applications challenging. In this paper we present Testdroid, an online platform for conducting scripted user interface tests on a variety of physical Android handsets. Testdroid(More)